docs: def overdrive(self, gain=20, colour=20):
          """overdrive takes 2 parameters: gain in dB and colour which effects
          the character of the distortion effet.
  
          Both have a default value of 20. TODO - changing color does not seem to have an audible effect
          """
          self.command.append('overdrive')
          self.command.append(gain)
          self.command.append(colour)
          return self